1. Field of the Invention
The present invention relates to a stereoscopic image display apparatus and a stereoscopic image display method.
2. Related Art
As a stereoscopic image or motion picture display apparatus which allows display of a motion picture, a so-called “a three-dimensional display”, various ones employing different systems have been known. In recent years, particularly, a demand for a display device of a flat panel type employing a system where it is not required to use dedicated eyeglasses or the like is increasing. As a stereoscopic motion picture display apparatus of such a type, there is known one utilizing a principle of holography, which is difficult to be put in a practical use. A system where an optical plate or a beam controlling element is installed just in front of a display panel (a flat display device) whose pixel positions are fixed, such as a liquid crystal display apparatus of a direct view type or a projection type, or a plasma display apparatus is known as a system which can be realized relatively easily. In this connection, the optical plate serves to control beams from the display panel to direct them to an observer or viewer.
The optical plate is generally called “a parallax barrier”, and it controls beams such that different images are viewed according to an angle change even at one or the same position on the beam control element. Specifically, when only lateral parallax (horizontal disparity) is applied, a slit array plate or a lenticular sheet (a cylindrical lens array) is used, and when an vertical parallax (a vertical disparity) is also included, a pinhole array or a lens array is used. The systems using the parallax barrier are also classified to a binocular system, a multiview system, a super-multiview system (super-multiview conditions in the multiview system), or an integral photography (hereinafter, also called “IP”). A basic principle common to these systems is substantially the same as that used in a stereoscopic photograph invented about a hundred years ago.
As described in SID04 Digest 1438 (2004), for example, the IP system of these systems has such a feature that the degree of freedom is high regarding a viewing point position and a stereoscopic view can be achieved easily. In the IP system which includes only horizontal disparity but does not include vertical disparity, a display apparatus with a high resolution can be relatively easily realized. On the other hand, in the binocular system or the multiview system, there is such a problem that it is difficult to see an image in a stereoscopic manner due to narrowness of a range of a view point position which allows a stereoscopic view, i.e., a viewing zone, but the simplest constitution can be adopted as a constitution for a stereoscopic image display apparatus and a display image can also be produced easily.
In a direct view type autostereoscopic image display apparatus using such a slit array plate or a lenticular sheet, moire or color moire occurs easily due to interference between a periodical structure about an aperture of an optical plate and a periodical structure about a pixel on a flat display apparatus. As a method for solving such a problem, a method where a direction in which the apertures extend is inclined obliquely has been known (for example, see JP-A-2001-501073).
However, when the apertures of the optical plate are provided obliquely, pixels at a stereoscopic image display (a stereoscopic display pixels) do not constitute a square arrangement but a parallelogram arrangement, so that when a stereoscopic image is composed by utilizing photographed images of multi cameras (multiview point images), it is necessary to perform arrangement conversion of the pixels. Such a problem arises that arrangement conversion based upon a simple processing caused degradation of image quality, arrangement conversion utilizing an interpolation or the like causes reduction in processing speed, and arrangement conversion based upon thinning of redundant data increases data amount. There is also such a problem that display characteristics bring discomfort to human vision characteristics due to that a higher direction of resolution becomes asymmetrical in a vertical direction and in a horizontal direction, motion parallax causes up and down movement, and so on.
As described above, in the conventional stereoscopic image display apparatus including the optical plate arranged obliquely, there is a problem about increase in image processing amount or display characteristics due to that such a fact that the pixel arrangement at the stereoscopic display is not the square arrangement.